Production of alk-1-en-6-ones

ABSTRACT

PRODUCTION OF ALK-1-EN-6-ONES BY REACTION OF AN ALK-1EN-4-OL AT FROM 100* TO 400*C. WITH A KETONE BEARING AT LEAST ONE HYDROGEN ATOM ON A CARBON IN VICINAL POSITION TO THE CARBONYL GROUP.

United States Patent 3,655,768 PRODUCTION OF ALK-l-EN-G-ONES HorstPommer, Ludwigshafen, Herbert Mueller, Frankenthal, and HermannOverwien, Ludwigshafen, Germany, assignors to Badische Anilin- &Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany NoDrawing. Filed Nov. 13, 1968, Ser. No. 775,518 Int. Cl. C07c' 49/20,49/45, 49/ 76 US. Cl. 260593 R 9 Claims ABSTRACT OF THE DISCLOSUREProduction of alk-l-en-6-ones by reaction of an alk-len-4-ol at from 100to 400 C. with a ketone bearing at least one hydrogen atom on a carbonatom in vicinal position to the carbonyl group.

The free valencies in the formulae are occupied by hydrogen orhydrocarbon radicals.

Among the alk-1-en-4-o1s' (II) to be used as starting materials, thoseare particularly suitable which have the general formula (Ila) I l H H(Ila) where the radicals R to R denote hydrogen or aliphatic,cycloaliphatic, araliphatic or aromatic hydrocarbon groups having upto'eight carbon atoms, some of these groups if desiredbeing linkedtogether in pairs to form five-membered to. seven-inembered rings.Especially suitable compounds are those in which four of the radicals Rto R denote hydrogen-atoms and the remaining radical is one of the saidhydrocarbon groupsi A large n'umberof com pounds (11a) is easilyaccessible by reaction of olefins (IV) with aldehydes (V) asshown:

Preferred starting materials (IIa) are those having four to ten carbonatoms, for examplebut-l-en-4-ol, Z-methylbut-l-en-4-ol, 3-methylbut-l-en4-ol, pent-Z-en-S-ol and2- cyclohexylbut-1-en-4-ol. The compoundsbutl-en-4-ol and 3,655,768 Patented Apr. 11, 1972 2-methylbut-l-en-4-olhave particular industrial importance.

Particularly suitable ketones (III) are those having the general FormulaIIIa:

R R (IIIa) where the radicals R to R each denotes a hydrogen atom or analiphatic, cycloaliphatic, araliphatic or arm matic hydrocarbon grouphaving up to eight carbon atoms, these groups if desired being combinedin pairs to form five-membered to seven-membered rings. Preferredcompounds (lIIa) are those having from three to eight carbon atoms, forexample acetone, methyl ethyl ketone, diethyl ketone, cyclohexenylmethyl ketone and acetophenone. Diethyl ketone and acetone haveparticular industrial importance.

When the ketone (III) is unsymmetrical and bears at least one hydrogenatom on both of the carbon atoms adjacent to the carbonyl group, amixture of two different compounds (I) is obtained.

According to observations made so far, the success of the processacording to this invention is not perceptibly dependent on the nature ofthe substituents on (III) and (HI), particularly on (11a) and (Illa)provided it is borne in mind that the reaction rate generally decreasesas the molecular size of these compounds increases. Undesired secondaryreactions, in particular the polymerization of (I) and (II) or (Ila) orthe intramolecular elimination of water from (H) or (IIa), may besuppressed as usual by operating in the presence of polymerizationinhibitors or in the presence of water under pressure. Moreover, it isoften advisable to accelerate the reaction in the desired direction byusing one of the reactants in an excess of up to twenty times.

The preferred reaction temperatures are from 200 to 350 C. Since most ofthe starting materials (II) and (III) which have special importanceindustrially would be gaseous at these temperatures at atmosphericpressure and since the reaction in liquid phase is preferred, it ispreferable to use superatrnospheric pressure (up to about 1000atmospheres), preferably the vapor pressure which is set up above thereaction mixture at the temperature chosen.

Since the products (I) of the process are themselves ketones which fallunder the definition for (III) and thus can undergo further reaction, itis advantageous to aim at low conversions or to use a large excess of(III). This procedure may best be carried out semicontinuously orcontinuously by a conventional method.

The reaction may be carried out with or without inert solvents ordiluents but in general one of the reactants serves as solvent.

When water is used as solvent or diluent, it is advantageous to maintaina constant pH value of from about 5 to 8 by means of-buffer substances.

Many alk-l-en-6-onesfare accessible by the process according to thisinvention and some of them are valuable perfumes or can be used asintermediates for the synthesis of the same. i v v The invention isillustratedby the following examples.

EXAMPLE 1 290 g. (5 moles) of acetone and 70 g. (0.8 mole) of2-methylbut- 1-en- 4-ol are heated in an autoclave for fortyfiveminutes, a pressure of about 220 atmospheres being set up. The reactionmixture is worked up by distillation. 42 g. of 2-methy1hept-1-en-6-onepasses over and 30 g. of 2-methylbut-1-en-4-ol is recovered. This is ayield of 72% with reference to the conversion; the conversion itself is57%.

3 EXAMPLE 2 290 g. moles) of acetone and 73 g. (1 mole) of but-1-en-4-ol are heated for one hour at 270 C. in an autoclave, a pressureof about 250 atmospheres being set up. The reaction mixture is worked upby distillation; hept-len-6-one is obtained in a yield of 63% withreference to a conversion of 50%.

EXAMPLE 3 280 g. (3.2 moles) of diethyl ketone and 70 g. (0.8 mole) of2-methylbut-1-en-4-ol are heated for forty-five minutes at 300 C., apressure of about 250 atmospheres being set up. The reaction mixture isworked up by distillation; 2,5-dimethyloct-1-en-6-one is obtained in ayield of 48% with reference to a conversion of 39%.

We claim:

1. A process for the production of an alk-l-en-6-one which comprisesreacting, at from 100 to 400 C., an alk-1en-4'ol of the formula:

R I l H wherein each of the radicals R to R when taken alone denotes ahydrogen atom or an aliphatic, cycloaliphatic or aromatic hydrocarbonradical having up to eight carbon atoms and wherein two of the radicalsR to R when taken together form a fiveto seven-membered carbocyclic ringand wherein the alkl-en-4ol contains a total of from four to ten carbonatoms, with a ketone of the formula:

wherein each of the radicals R to R when taken alone denotes a hydrogenatom or an aliphatic or cycloaliphatic 4 hydrocarbon radical and whereintwo of the radicals R to R when taken together form a fivetoseven-membered carbocyclic ring and wherein the ketone contains a totalof from three to eight carbon atoms.

2. A process as claimed in claim 1 wherein four of the radicals R to Rdenote hydrogen atoms and the remaining radical denotes one of the saidhydrocarbon radicals.

3. A process as claimed in claim 1 wherein but-1-en-4- 01 or2-methylbut-l-en-4-ol is used as the alk-l-en-4-ol.

4. A process as claimed in claim 1 carried out at from 200 to 350 C.

5. A process as claimed in claim 1 carried out at a pressure of up toabout 1000 atmospheres.

6. A process as claimed in claim 1 wherein said ketone reactant isselected from the group consisting of diethyl ketone and acetone.

7. A process as claimed in claim 1 wherein the ketone reactant isacetone and the alkenol reactant is Z-methylbut-1-en-4ol.

8. A process as claimed in claim 1 wherein the ketone reactant isacetone and the alkenol reactant is but-l-en- 4-ol.

9. A process as claimed in claim 1 wherein the ketone reactant isdiethyl ketone and the alkenol reactant is 2- methylbut- 1-en-4-ol.

References Cited UNITED STATES PATENTS 3,326,978 6/1967 Dunkel 260593 RDANIEL D. HORWIT Z, Primary Examiner US. Cl. X.R.

- $55533 K UNITED y-xurzss PATENT OFF CE CERTIFICATE OF CORRECTION jIce'np No. j 3,655,768 Dated Ap il 11.. 1972 ",Iflwuibfls)ffiorst;Pommer, Herbert Mueller, and HemnanLQve 91-min 1 i"; 'i s 'certifiedthat error appears in the above-identified patent 'and that said LettersPaten; are hereby correcteias shown below:

Cqlumn '1, line 8, in the heading, after 775,518 insert-- Claimspriority, application Germany, November 17, 1967,

,P 16 #3 696.! lines 33 to &2, should read (II)- 1 (III) L I jSigned-and sealed thi 28th day of NbIfer r Iber 1972.

SEAL) v t'es tz' I I EDWA D MJLEIGEIR R; ROBERT eo'rsrsmix I flj i testing" ()izt'i'cem Commissioner of Patents

